It is very important to remove dust, lint and other such particulate matter from surfaces prior to their painting, since such contaminants can produce a variety of blemishes in the final painted finish. Cleaning is particularly important in those instance where it is desirable to achieve large area, high quality painted finishes, as for example in the manufacture of motor vehicles. It is essential that any pre-painting cleaning process not mar the vehicle or introduce any new contaminants. Furthermore, it is desirable that any cleaning process be compatible with high volume automated manufacturing techniques.
Originally, pre-painting cleaning was carried out by wiping the surfaces with cloths impregnated with a tacky material, and hence, all such cleaning processes are generally referred to as "tacking" or "tack-off" processes. Cloth based processes have been found to be generally unsatisfactory, and the art has turned to various brush based systems. Apparatus of this type generally comprises a rotating brush which is swept across the surface to be cleaned. The brush removes dust particles which are collected by a vacuum. One such prior art system particularly adapted for cleaning motor vehicle bodies is shown in U.S. Pat. No. 4,689,749.
A number of problems have been encountered with prior art tack-off systems, particularly as applicable to the manufacture of motor vehicles. Brush positioning and control is critical, since it is necessary that the brush sweep the entire vehicle surface. However, it is important to avoid inadvertent collision of the brush with the vehicle. The brushes are typically manufactured from ostrich feathers and are expensive and fragile; furthermore, an inadvertent collision can also mar the vehicle surface. Problems of brush control are further complicated by the fact that most vehicular bodies are of fairly complicated design, and in most instances, a particular tack-off system will be employed to prepare a number of different vehicular body types. It is also most important that any tack-off machine not introduce any new contaminants to the cleaned vehicle surface. In many prior art tack-off machines, the vacuum collection system includes a number of flexible conduits, and these conduits are frequently disposed in a location above the path of travel of the vehicle being cleaned, and one such prior art system having overhead conduits is shown in U.S. Pat. No. 4,689,749. In accord with the present invention, it has been found that these conduits can become a significant source of contamination. The present invention recognizes that it is important to properly position, and eliminate the number of conduits in a tack-off system in order to prevent recontamination of the cleaned surfaces.
As will be described in greater detail hereinbelow, the present invention provides an improved tack-off machine which accurately controls brush position to maximize cleaning effect while minimizing the possibility of marring the vehicular surface. The machine of the present invention also provides improved cleaning efficiency and prevents recontamination of the cleaned surface by optimizing the configuration of collection conduits. These and other advantages of the present invention will be readily apparent from the drawings, discussion and description which follow.